The Multimedia Broadcast/Multicast Service Single Frequency Network (MBSFN) technology is an enhanced version of the Multimedia Broadcast/Multicast Service (MBMS) technology. Under the MBSFN mode, all of the neighboring base stations synchronously transmit identical radio signals. A terminal can treat signals that came from different base stations as multi-path signals, and performs over-the-air signal combining on these multi-path signals in order to increase receive gain of signals, thus improving the receiving effect of signals.
However, when a universal terrestrial radio access network (UTRAN) transmits signals for some MBMS service, e.g. a television channel, using the MBSFN mode, it is necessary to configure a special scrambling code for said service. The scrambling code is related to the service, i.e. different cells need to use the same scrambling code when transmitting identical television channel signals, so as to ensure that the terminal can perform combining on these signals. Hence, the UTRAN needs to plan for service-related scrambling codes, and ensures that these service-related scrambling codes are different from cell scrambling codes, thus bringing forward new requirements of network planning/optimization to the service provider, increasing design difficulty and cost requirement.
In the conventional technology, chip combining is often utilized for MBMS service. Specifically, when different cells are transmitting identical television channel signals, these cells still use their respective scrambling code to scramble the television channel signals. When a terminal is receiving television channel signals from different cells, though the scrambled television channel signals have different radio signals, the user equipment (UE) uses the chip combining mode, i.e. the multi-cell joint detection method, to perform chip-level combining on the received television channels of different cells so as to increase the receive gain of the signals, thus improving the signal receiving effect. Each neighboring cell has a unique neighboring cell identifier, and contains multiple S-CCPCH channels. When an MBMS service needs to perform chip combining, it designates the chip combining mode to the multiple S-CCPCH channels that are carrying this MBMS service; a terminal receives this message, then for each MBMS service of its interest, the terminal receives the configuration information of the S-CCPCHs that are carrying this MBMS service in the local cell as well as in neighboring cells that support said MBMS service, and performs continuous chip combining.
When using this technology for the scheduling of the S-CCPCHs that carry the same MBMS service, once the multiple cells that carry said service are determined, the carrying method is indicated in the message described above, and until said message is transmitted again, the carrying method for said service is required to remain unchanged for the cells that carry said service. In other words, the terminal continuously performs chip combining with neighboring cells in this period of time, based on the scheduling information of the S-CCPCHs that carry the MBMS service in the local cell and the neighboring cells. However, in practice, because the demand of resource scheduling is different for different neighboring cells, for the same MBMS service the service carrying status may have changed before the above described message is transmitted again. For example, the shopping information service of a shopping mall, the scheduling cycle of this MBMS service can be very short in the shopping mall (i.e. the local cell), since the mobile users in the shopping mall will not be put off by the frequent receiving of the shopping information; however, in the cells close to the shopping mall (i.e. the neighboring cells) the scheduling cycle of the MBMS service should be relatively long, otherwise the frequent receiving of advertisement-based shopping information may cause offence to the mobile users in these cells.
The conventional system and method has the following disadvantages: The chip combining technology requires that, for the same MBMS service, different cells must have consistent service carrying status during the time period from the end of the last transmission of the control information to the beginning of the next transmission of the control information, while the terminal continuously performs chip combining on these different cells. The technology lacks the mechanism for discontinuously scheduling the S-CCPCHs (which is used for chip combining) of neighboring cells, thus can not adapt to the situation where the same MBMS service is discontinuously scheduled in different cells. Therefore, there is a need for a method and system to overcome these disadvantages.